ml
60 lines
1.4 KiB
Go
60 lines
1.4 KiB
Go
package compression
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import "github.com/inkyblackness/hacked/ss1/serial"
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// WordWriter serializes a stream of word entries.
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type WordWriter struct {
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coder serial.Coder
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bufferedBits uint
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scratch uint32
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outBuffer [1024]byte
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outUsed int
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}
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// NewWordWriter returns a new instance.
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func NewWordWriter(coder serial.Coder) *WordWriter {
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writer := &WordWriter{coder: coder, bufferedBits: 0, scratch: 0}
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return writer
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}
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// Close finishes the stream of words.
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func (writer *WordWriter) Close() {
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writer.Write(EndOfStream)
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if writer.bufferedBits > 0 {
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writer.writeByte(byte(writer.scratch >> 16))
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}
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writer.writeByte(byte(0x00))
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writer.flushBuffer()
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}
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// Write adds the given word to the stream.
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func (writer *WordWriter) Write(value Word) {
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writer.scratch |= uint32(value) << ((16 - bitsPerWord) + (8 - writer.bufferedBits))
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writer.bufferedBits += bitsPerWord
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writer.writeByte(byte(writer.scratch >> 16))
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writer.scratch <<= 8
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writer.bufferedBits -= 8
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if writer.bufferedBits >= 8 {
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writer.writeByte(byte(writer.scratch >> 16))
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writer.scratch <<= 8
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writer.bufferedBits -= 8
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}
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}
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func (writer *WordWriter) writeByte(value byte) {
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writer.outBuffer[writer.outUsed] = value
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writer.outUsed++
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if writer.outUsed >= len(writer.outBuffer) {
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writer.flushBuffer()
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}
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}
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func (writer *WordWriter) flushBuffer() {
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writer.coder.Code(writer.outBuffer[:writer.outUsed])
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writer.outUsed = 0
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}
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